Broadening of 1H NMR signals in the spectra of heparin and OSCS by paramagnetic transition metal ions. The use of EDTA to sharpen the signals.

Some signals in the (1)H NMR spectra of heparin and oversulphated chondroitin sulphate (OSCS) are occasionally broad or very broad owing to the presence of paramagnetic metal ions in those polysaccharides. The addition of very small amounts of EDTA to heparin or to OSCS contaminated heparin solutions was needed to obtain normal looking spectra.